With a following patch, find_thread_ptid will first find the inferior
for the passed-in ptid, using find_inferior_pid, and then look for the
thread in that inferior's thread list. If we pass down null_ptid to
find_thread_ptid then that means we'll end up passing 0 to
find_inferior_pid, which hits this assertion:
> struct inferior *
> find_inferior_pid (int pid)
> {
> struct inferior *inf;
>
> /* Looking for inferior pid == 0 is always wrong, and indicative of
> a bug somewhere else. There may be more than one with pid == 0,
> for instance. */
> gdb_assert (pid != 0);
This patch prepares for the change, by avoiding passing down null_ptid
to find_thread_ptid or to functions that naturally use it, such as the
target_pid_to_str call in inferior.c:add_inferior. In that latter
case, the patch changes GDB output,
from:
(gdb) add-inferior
[New inferior 2 (process 0)]
to:
(gdb) add-inferior
[New inferior 2]
which seems like a good change to me. It might not even make sense to
talk about "process" for the current target, for example.
The python_on_normal_stop change ends up avoiding looking up the
same thread twice (inferior_thread also does a look up).
gdb/ChangeLog:
2018-11-22 Pedro Alves <palves@redhat.com>
* cli/cli-interp.c (cli_on_user_selected_context_changed): Use
inferior_thread instead of find_thread_ptid, and only when
inferior_ptid is not null_ptid.
* inferior.c (add_inferior): Don't include target_pid_to_str
output when the inferior is not started.
* python/py-inferior.c (python_on_normal_stop): Don't use
find_thread_ptid.
(tui_on_user_selected_context_changed): Use inferior_thread
instead of find_thread_ptid, and only when inferior_ptid is not
null_ptid.
Pedro Alves